The present invention relates to the art of color proofing, and in particular, to a method of preparing a two sided pre-press proofs such as by the use of pressure and heat to laminate media together.
Pre-press proofing is a procedure that is used primarily by the printing industry for creating representative images of printed material. In the printing industry pre-press proofs are used to check for color balance, control parameters and other important image quality requirements, without the cost and time that is required to actually produce printing plates, set up a printing press, and produce an example of a representative image, which would result in higher costs and a loss of profits that would ultimately be passed on to the customer.
To create a pre-press proof first an original image is separated into individual color separations or digital files. The original image is scanned and separated into the three subtractive primaries and black. Typically a color scanner is used to create the color separations or digital files and in some instances, more than four color separations or digital files are used. Although there are several ways used in the printing industry to create a pre-press proof from the color separations or digital files they are generally one of three types. The first method being a color overlay system that employs the representative image on a separate base for each color, which are then overlaid to create a pre-press proof. The second, a single integral sheet process in which the separate colors for the representative image is transferred one at a time by lamination onto a single base. Third, a digital method in which the representative image is produced directly onto a receiver stock, or onto an intermediate sheet then transferred by lamination onto a receiver stock from digital files.
The representative image to be laminated can be created on, but is not limited to, a commercially available Kodak image processing apparatus, depicted in commonly assigned U.S. Pat. No. 5,268,708, which describes an image processing apparatus having half-tone color imaging capabilities. The above-mentioned image processing apparatus is arranged to form a representative image onto a sheet of print media in which colorant from a sheet of colorant donor material is transferred to the print media, by applying a sufficient amount of thermal energy to the colorant donor sheet material to form the representative image. The image processing apparatus is comprised generally of a material supply assembly and a lathe bed scanning subsystem. The scanning subsystem includes: a lathe bed scanning frame, translation drive, translation stage member, printhead, imaging drum, and media exit transports.
The operation of the image processing apparatus comprises of metering a length of the print media (in roll form) from the material supply assembly. The print media is then measured and cut into sheet form of the required length and transported to the imaging drum, registered, wrapped around, and secured onto the imaging drum. Next, a length of colorant donor material (in roll form) is also metered out of the material supply assembly, then measured and cut into sheet form of the required length. It is then transported to the imaging drum and wrapped around the imaging drum utilizing a load roller which is described in detail, in commonly assigned U.S. Pat. No. 5,268,708, such that it is superposed in the desired registration with respect to the print media (which has already been secured to the imaging drum).
After the colorant donor sheet material is secured to the periphery of the imaging drum the scanning subsystem or write engine provides the imaging function. This image function is accomplished by retaining the print media and the colorant donor sheet material on the imaging drum while it is rotated past the printhead. The translation drive traverses the printhead and translation stage member axially along the axis of the imaging drum, in coordinated motion with the rotating imaging drum. These movements combine to produce the representative image on the print media.
Once the representative image has been formed on the print media, the colorant donor sheet material is then removed from the imaging drum. This is accomplished without disturbing the print media that is beneath it. The colorant donor sheet material is then transported out of the image processing apparatus by means of the material exit transport. Additional colorant donor sheet materials featuring other desired colorants are sequentially superimposed with the print media on the imaging drum and then imaged onto the print media as previously mentioned, until the representative image is completed on the print media. The representative image formed thereon is then unloaded from the imaging drum and transported by the receiver sheet material exit transport to an exit tray in the exterior of the image processing apparatus.
After a representative image has been formed on the print media as previously described it is transferred to a receiver stock such that the pre-press proof is representative of the image to be printed on a printing press. A Kodak laminator as described in U.S. Pat. No. 5,478,434 can be used to bond or laminate the representative image as a part of a pre-press proofing system. As additional references U.S. Pat. No. 5,203,942 describes a Kodak laminator that employs a lamination/de-lamination system as applied to a drum laminator and pending U.S. patent application Ser. No. 09/676,877, filed Sep. 29, 2000, describes a Kodak laminator that employs endless belts incorporated into the lamination apparatus. For the purpose of this patent application the laminator described in U.S. patent application Ser. No. 09/676,877 will be used. It should be noted that the present invention described in this disclosure is not limited to a Kodak laminator or type of laminator referenced above.
The receiver stock can be sheet-fed press printing stock, specially coated paper stock, or previously laminated stock. In this latter case a sheet of pre-laminate, which has a pre-laminate support layer consisting of a suitable base material, optionally coated with a releasing material, and a thermal print layer, is placed on top of a receiver sheet, which is also called receiver stock in the industry. This construction of multiple layers is a lamination sandwich, which is fed into the laminator. Once the lamination sandwich exits the laminator the pre-laminate support layer is peeled away from the now pre-laminated receiver stock. Any of the laminators referred to above can be used to affect the transfer of the pre-laminate receiving layer to the receiver stock.
Although the above described lamination method works well for most pre-press proofs and for both laser thermal and inkjet pre-press proofs. There exists a need for an improved method of laminating dual sided pre-press proofs and improving the registration of the intended images on opposite sides of the pre-press proof.
The present invention provides a method for laminating a dual sided pre-press proof that comprises laminating a first side of a receiver stock with a first pre-laminate sheet. The first pre-laminate sheet has a first pre-laminate sheet support layer and a first pre-laminate sheet release layer. Laminating a second side of the receiver stock with a second pre-laminate sheet. The second pre-laminate sheet has a second pre-laminate sheet support layer and a second pre-laminate sheet release layer. Both the first and second pre-laminate sheets could be laminated to the receiver stock at the same time. The first pre-laminate sheet support layer and the second pre-laminate sheet support layer are removed forming a pre-laminated receiver stock. A first imaged clear receiver sheet with a first clear support layer, first clear release layer, and first image registration marks are created. A second imaged clear receiver sheet with a second clear support layer, second clear release layer, and second image registration marks are created. Laminating the first and second imaged clear receiver sheets to the pre-laminated receiver stock, with the first and second imaged clear receiver sheets on opposite sides of the pre-laminated receiver stock overlapping the pre-laminated receiver stock such that the registration marks on the first and second imaged clear receiver sheets are visibly positioned on top of each other and are in registration with each other. The first clear support layer and the second clear support layer is removed forming a dual sided pre-press proof, wherein the images are in registration with each other.
The invention also relates to a method for laminating a dual sided pre-press proof that comprises creating a first and second imaged clear receiver sheet each with a clear support layer, clear release layer, and registration marks. Laminating the first and second imaged clear receiver sheets to a receiver stock, with the first and second imaged clear receiver sheets on opposite sides of the receiver stock overlapping the receiver stock such that the registration marks are visibly positioned on top of each other and in registration with each other. The clear support layers from the first and second imaged clear receiver sheets are removed forming a dual sided pre-press proof, wherein the images are in registration with each other.